Soluble benzyl ether of dextran



' Patent No. 2,203,703, dated June 11, 1940.

Patented July 31, 1945 UNITED STATES PATENT- orrics 7 2,380,879 1SOLUBLE BENZYL OF Grant L. Stahly, Columbus, Ohio, and'Warner W.Carlson, Pittsburgh, Pa., assignors to Chemical DevelopmentsCorporation, Dayton, Ohio, a corporation of Ohio No Drawing. Originalapplication February 26, 1938, Serial No.. 192,887, now Patent No.2,328,036, dated August 31, 1943.. Divided and this applicationMarch-31, 1944, Serial No.

' 1 Claim. (01.260-209') This invention dealswith soluble benzyi etherof dextran and is a division 01' the following prior applications:

Serial No. Date iiled Patent No. Date granted 192, 887 Feb. 1998.--. 2328,030 A 3i 1943. 415,936 Oct. 321041---.

470, 802 Dec. 31, 1942 496, 361 July 19, 1943 495,302 -d Moreparticularly this invention deals with benzyl ether of dextran soluble.in commercial solvents oi the general type employed for dissolvnsnitrocellulose. 1

In our prior patent No. 2,203,704, dated June 11, 1940, we havedescribed and claimed a method of producing ethers of dextran whichareinsoluble in the aforementioned type of solvents. The products resultingfrom the practice or said method are described and claimed in our priorIn the practice 01 the present invention destran and benzyl chloride arecaused to react in the Presence of alkali such as sodium hydroxide,

whereby the benzyl radical is substituted for the hydrogen atom in oneor more of the hydroxyl groups in the dextran molecule to produce asol-' uble product. The degree oi. solubility of the re-'sulting'product will depend upon the number of benzyl radicalsin eachanhydroglucose unit.

The procedure followed in the production of the soluble benzyl ether ofdextran of our invention includes reaction 01 benzyl chloride anddextran in mole ratios 01 approximately from 2:1

to 7.5:1. The procedure rurther provides a two stage process whereby aninsoluble benzyi dextran is first obtained which thereafter undergoessubstitution or additicnai hydrogen atoms by benzyl radicals in thehydroiryi groups of the not oi the stage otthe procedure hereindescribed and claimed.

Furthermore, the present application deals with certain improvements ofthe process described and claimed in our prior Patent No. 2,203,- 704,dated June 11, 1940, whereby it is possible to obtain acetone solublebenzyl ether of dextran in a single step by proper selection, controland adjustment or reaction conditions, instead 01' the acetone insolubleother obtained according to the process of said patent, as will be moreclearly set forth in certain oi the typical examples hereinafter to begiven. I t

The soluble benzyl ether of dextran resulting from the practice 0! thepresent invention is eminently well adapted to provide protective anddecorative coatinss which can be applied by brushin: or-rolling orspreading but preferably by sprayinl. said coatings being characterisedby a rapid rate of dryinz. high adhesion to supporting surfaces andtheir ihertness to water, certain acids, alkalis, alcohols and othersimilar soldextran molecule to yield a soluble product. In

other words, an insoluble dcxtran product such as produced according toour prior Patent No. 2,203,204, dated June 11, 1940-(see claim 6 therebesubstantially ivalent tothe prodvents, and by having 'high solubilityincertain low priced solvents whereby the product of our invention ismade available for use as an industrial coatinz. Furthermore, suchcoatings are substantially non-inflammable and form hard, substantiallyclear, impervious, flexible films without the'use of plasticizers,fire-retardants and resins. Such compositions are described and claimedin our prior Patents No. 2,203,705, dated June 11, 1940, and No.2,236,386, dated March 25, 1M1.

Paocsss or Barman-Ion V degrees C. for six hours.

It has been shown that dextran has one of the following formulas:

to 145 degrees C. for four hours. Soluble benzyl dextren was obtained.

H on on on HJJ-OH noon noon noon o Boo-n no 11 noon noon 13 H g H -on Hon n on Ho-- -0-c-o- 433,011

a n H o H n H n H H H H|-- Hr-- n,-- Hr- 1 i l l H- on on on n on H onnoon noon 110 H 0 H0 H 0 o noon 0 noon H OH H on H on H H H H no a H 5.o H 0 H H H,------- H:-() CC-C- CHOH n H o H n It is apparent that theprimary unit of the dex- Emma: 11

tran molecule is a chain of four anhydroglucose residues joineduniformly by glucosidic linkages between the first and sixth carbonatoms of contiguous hexose units. According to Formula I, the fourthhexose unit carries a side chain of one anhydroglucose residue on carbonatom No. 4; according to Formula II, the side chain anhydroglucose unitis attached to the sixty carbon atom and attachment is made to the restof th molecule through carbon atom No. 4. It is not known how many ofthese five anhydroglucose units there are in a molecule of dextran butthe presence of the side chain separates it definitely in structure fromsuch common polysaccharides as starch and cellulose.

When benzyl chloride is heated with dextran in the presence of sodiumhydroxide the benzyl radical is substituted for the hydrogen atom in oneor more of the hydroxyl groups in the dextran molecule (see Examplesland 11). The acetone-sol uble product contains more benzyl radicals ineach anhydroglucose uhit than does the acetonein soluble product. Thesoluble product 13 the one described herein.

,The following are typical examples of. the process. It will beunderstood that the proportions indicated are relativ and approximate inthe sense that further experience may indicate modifications of theproportions, depending on the type of production machinery employed andother tac- To 30 grams of dextran in 100 cc. of water were added 93grams of benzyl chloride (mole ratio of 4:1) and 32 grams of sodiumhydroxide, and the mixture refluxed with stirring for 0.5 hour atdegrees to degrees C. The temperature was thenraised to and held at 135to 140 degrees C. for 0.5 hour. Again it was slowly raised so that atthe end of 1.5 hours it stood at 1'75 to 185 degrees 0., where it washeld for an additional 1.5 hours. The total heating period was threehours and the yield of soluble benzyl dextran was good.

EXAIPLI III 75 to 80 degrees C'Jwith stirring for 0.5 hour.

tors. Modifications of temperature, time and pressure may, likewise, bedesirable. Mole ratios refer to molecular weishts oi benzyl chlorideused for each hexose unit of dextran'.

EXAIPLI I To 30 grams of dextran dissolved in cc. of water were added46.5 grams of benzyl chloride (mole'ratio 01 2:1) and 17 grams of sodiumhydroxide, and the mixture refluxed at to Then 46.5 grams of benzylchloride (total mole ratio or benzyl chloride to dextran, 4:1) and 1'1grams or sodium hydroxide were added, and heating continued at 185 Then23.5 grams of benzyl chloride (total mole ratio oi 3:1) and 10 grams ofsodium hydroxide were added, and the temperature raised slowly so thatat the end of the first hour it stood at to 185 degrees C., where it wasmaintained for two hours. Soluble benzyl dextran results.

Emu: IV

EXAMPLE V Dextran m 30 Benzyl chloride gm 90 Sodium hydroxide --gm 40The product resulting from heating together these materials attemperatures from 140 to degrees C. for 3 to 6 hours is steam-distilled.Other methods may be employed. The resulting product is soluble in suchsolvents as acetone.

Cellosolve, dioxane, ethyl acetate, dlacetone, mesityl oxide andchloroform.

M EXAMPLEVI "It vhas been found that. "the addition =to .tlie productresultin from Example .V (after the .su pernatant liquid has beenpouredfofil Qfgza econd batch-10f 90 grams of benzyl chloride, -4Q:gramsof sodium hydroxide, and 20000. of water, and the reheating vof thematerials under reflux for an additional sixflhours gives a desirableproduct.

attests of acetone-soluble benzy ldextran was 48 grams,

of '76- percent ofxthe theoretical.

The reaction mixture is steam distilled to recover .gra .ms of benzyldextran, representing a :yield of '59 per cent -of "the theoreticalamount of 63 grams was obtained. The molecular ratio was '6 moles ofbenzyl chloride to 1 of dex tran.

a PPE :V f

To 30-grams of-deXtran dissolved in 100110. of water were added 1 1'7 .5grams :of benzyl chloride and 38 grams of sodium hydroxide, andthemixture refluxed forten hours at 105 degrees. to 110 degrees C. With thesame purification: 'procedureas was described before, '28 gramsof'benzyl dextran were cbtained, a yield of 44 percent .of the theoretical;"The molecular ratio :of ben-zyl chloride to dextranin' this case was5:1. 1

EXAMPLE IX To 30 grams of dextrandissolved in 100 cc. of Water wereadded 93 grams of .benz'ylchloride and 82 grams of sodium hydroxide; andthe mixture refluxed at -l05degrees 'to 110 degrees C. for tenhoursiAfter the usual purification, .a yield'of 12 grams (19 per cent.)ofnacetone-soluble, and 23 grams (37 per. cent) of acetone-insolublebenzyl dextran were 1 obtained. The

molecular ratio of benzyl chloride to dextran was- To 30 grams ofdextran dissolved in 100 cc. of water were added 23.5 grams-ofsbenzylchlm ride (mole ratio of 1:1) and 10. gramsoi sodium hydroxide, and themixture heated at 105 to 110 degrees C. for six *hoursp At the end ofthis time, '70 grams of *benzyl chloride (bringing the final mole ratioto 4:1) and 25 grams of sodium hydroxide were added and heatingcontinued at 135 to 140 degrees C. for 4 hours more. Thirtyone grams (49per cent yield) of acetone-soluble benzyl dextran were obtained.

EXAMPLE XI To 30 grams of dextran dissolved in 100 cc. of water wereadded '70 grams of benzyl chloride (mole ratio of 3:1) and 25 grams ofsodium hydroxide, and the mixture heated as before at 105 to 110 degreesC. for 6 hours. With the addition of 23 grams of benzyl chloride(bringing the total mole ratio to 4:1) and grams of sodium hydroxide,the mixture was heated for an additional 4 hours at 135 to 140 degreesC. The yield grams of dextran were added 47 grams of benzyl chloride(mole ratio ofl2z1.) and 16 grams of sodi- L ExA rrJEIXII of dextrandissolved in E00 (cc. of water were 1 added 58:75 grams of bound chlo-To 30 grams ridelmole' ratio of. 25:1) and 20 grams of sodium hydroxide,and the mixture heatedwithstirringdor 3. 5 hours at "to '80 degrees C.At the end of this time, 353' grams of :benzyl chloride (bringingthe-total mole ratio to 4zl) and 12 grams of sodium hydroxide wereadded, and heating continued at 135 to 145 degrees Cyfor 0.5 hour,

and then at "17-5 to 185 degrees C. for 2 hours. The total period ofheating was 6 hours.

EXAMPLETZQII I To30 grams of dextran in .100 cc. of water were added 93grams of benzyl chloride (mole ratio of 4:1). and 32 grams of sodiumhydroxide and the mixture heated altto D s r 0.5 hour. During the nextone-half hour the temperature was slowly raised so that at the end oft-he first' hour of heating it stood at 135 to 1140 degrees (land it Wasthen further raised to 175 to 185 degrees C. where it was held for aperiod of three hours giving a total heating period of four hours.

* EXAMPLE XIV 'To 375 cc-of :a culture medium containing 30 umhydroxide, and the solution heated at 75 to BO-degrees C. for 0.5 hourswith stirring. The temperature was-then raised and held :at .105 todegrees .C. for one liour. Eorty-seven-grams of benzyl chloride (makingthe total mole ratio 4:1) and 16 grams of sodium hydroxide were added,the =mixturezheated at degrees to degrees -C. for' one hour, and :at todegrees C. "for'three hours.

I I A SOLVENTS The following is a table giving. the solubilitycharacteristics 'of this product:

I Isoamyl alcoho Solvent Soluble :Insoluble Softens Methyl alcohol"Ethyl .alccholu Massages Acetone Diacetone Ghloroicrm.

enzeneulu Toluene Massa es Two points of particular interest are to benoted in the table: (1) the insolubility of the benzyl dextran in water,alkalis, acids and the common alcohols, and (2) its solubility in thecheap commercial solvents, acetone, ethyl acetate and butyl acetate. Byproperly regulating the proportions of these solvents in the finishedlacquer it is possible to obtain a wide variation in the rate of drying.It is comprehended within the term solvent or the use of the termsacetone, butyl acetate or ethyl acetate, such other equivalent solventsas may from time to time be available in this connection. Under somecircumfirst stage may be from '75 to degrees C. (Examples III and X11);'75 to 110 degrees C. (Example XIV) to degrees C. (Examples I,

X and XI); and to 180 degrees C. (Example VI). In the second stage'o-fthe reaction the temperature may be from 135 to degrees C. (Examples I,X and XI); 135 to-l40 (Examples X and XI) 120 to degrees C. (ExampleXIV) {I and to 185 degrees C. (Example III).

It'will be also noted by reference tothe examples given herein that themole ratio of benzyl chloride to dextran during the first stage may befrom 1:1 (Example X) to 4:1 (Example VI). In the secondstage of thereaction the mole ratio of benzyl chloride to dextran may befrom 3:1(Example III) to 7511 (Example VI).

It will be noted in addition that the Weight ratio of dextran to sodiumhydroxide during the (Example VI) and that in the second stage it may befrom 312.6 (Example III) to 3:.8 .(Example VI). Furthermore, it will benoted that during the first stage the reaction period may be fromonehalf hour (Example III) to six hours (Examples I, X and XE) and thatduring the second stage it may be from two hours (Example III) to sixhours (Example VI).

With reference to the single-stage method, it

will be noted by reference to the examples given herein that thetemperature may be from '75 to 185 C. (Example II). It will also benoted that the mole ratio of benzyl chloride to dextran may be from 4:1(Examples II, V, IX and XIII) to 6:1 (Example VII). Furthermore, it willbe noted that the weight ratio of dextran to sodium hydroxide may befrom 3:3.2 (Examples II, IX and XIII) to 3:4.5 (Example VII). Inaddition, it will be noted that the reaction time may be from threehours at from 75 to 185 C. (Example II) to .ten hours at 105 to 110 C.(Examples VII, VIII and IX). In other words, while the reaction timeincludes the range disclosed and claimed in our prior Patent No.2,203,704, dated June 11, 1940 (the product of which is insoluble insolvents of the class herein disclosed), the time-temperaturerelationship differs. Lower temperatures require longer treatment, andhigher temperatures shorter the examples 30 first stage may be from.3:l(Example X) to 3:4

treatment. The time-temperature relationship disclosed in the examplesherein differs from that employed in the investigation which led to theinvention disclosed and claimed in our said prior Patent No. 2,203,704.

In pointing out the mole ratio range of benzyl chloride to dextran andthe weight ratio range of dextran to sodium hydroxide in the singlestagemethod, we have not made reference to Example IV (which shows lowerratios) because of the fact that it covers an experiment conducted undersuperatmospheric pressure and therefore not directly comparable with theother examples.

The dextran itself is produced by bacterial action and the benzyl etherof dextran therefore may-be considered-as the product of combinedbacteriological and chemical action such as described in our priorPatents Nos. 2,203,702; 2,303,703; and 2,203,704, all dated June 11,1940. Whenever the methods disclosed in said applications are followed,such methods should be modified in accordance with the disclosureherein.

As has been stated hereinbefore, the reaction is carried out in twostages; firstly, the insoluble benzyl dextran is produced and secondly,substitution of additional hydrogen atoms by benzyl radicals in thehydroxyl groups is made to yield a soluble product. However, as it alsohas been stated hereinbefore, a single-stage procedure may be used ifproper selection, control and adjustment of the reaction conditions ismade.

It will be understood that while we have herein described certainembodiments of our invention, it is not our intent thereby to have itlimited to or circumscribed by the specific details of procedure andproportions indicated in view of the fact that our invention is adaptedto modifications within the spirit of our disclosure and the scope ofthe appended claims.

We claim:

The 2-stage method of producing soluble benzyl ether of dextran whichcomprises: heating together 30 grams of dextran, 90 grams of benzylchloride, and 40 grams of sodium hydroxide at a temperature of from 140to C. for a period of from 3 to 6 hours; decanting the supernatantliquid; adding to the residue 90 grams of benzyl chloride, 40 grams ofsodium hydroxide, and 200 cc. of water, and reheating the mixture underreflux for an additional period of 6 hours;

and thereafter removing benzyl chloride and benzyl alcohol from theresulting mixture whereby there is produced a benzyl ether of dextransoluble in solvents of the class consisting of acetone, Cellosolve,dioxane, ethyl acetate, diacetone,

mesityl oxide, and chloroform.

WARNER W. CARLSON. GRANT L. ST AHLY.

